Basically, you are very well protected with the use of a VPN service. We nevertheless advise countermeasures against IP Leaks due to WebRTC (Web Real-Time Communication). You can see if you are vulnerable from this problem with our WebRTC Leak check
There are two approaches to protecting against an IP leak. One option in Chrome is to install WebRTC Leak Prevent add-ons / plugins to manage potential IP leaks. Also available since the end of 2016 is the extension Easy WebRTC Block, which also exists in a version for Opera.
The other option is to change the settings in the browser.
In Firefox, about: config can set the value media.peerconnection.enabled to false, which prevents an IP leak.
More about WebRTC at: https://en.wikipedia.org/wiki/WebRTC